Asteroid that killed off dinosaurs almost eradicated mammals too

The giant asteroid that is credited with killing off the dinosaurs at the end of the Cretaceous period almost ended mammalian hopes of survival, too.

A new study into the bridge between the Cretaceous and Paleogene boundary – that bridge being a major asteroid that rocked the planet – suggests it was perhaps more deadly than first thought.

Originally thought to have killed off the dinosaurs, leaving mammals relatively better off, researchers from the University of Bath claim that almost every mammal was wiped out too.

The difference between mammals – no larger than cats – and dinosaurs is that they bounced back exceptionally well, doubling species numbers remarkably quickly.

93pc of all mammals on the planet were killed off by the event, according to Dr Nick Longrich, whose team published its work in the Journal of Evolutionary Biology.

Those that survived would have had to live off the scant plants that remained alive, animals which were killed or slowly died off, or even insects that survived the impact.

“Because mammals did so well after the extinction, we have tended to assume that it didn’t hit them as hard,” said Longrich.

“However, our analysis shows that the mammals were hit harder than most groups of animals, such as lizards, turtles, crocodilians, but they proved to be far more adaptable in the aftermath.”

Dr Nick Longrich from the Milner Centre for Evolution at the University of Bath co-authored the study, via Anthony Prothero

Longrich and his team applied larger data sets to previous assumptions, which revealed far more impact on mammals on Earth. The subsequent bounce back – doubling species numbers in just 300,000 years – shielded the true damage. It also led to a planet dominated by an adaptive collection of mammals.

What helped was the diverse collection of mammals, too. Whereas dinosaurs’ evolution was limited, and their diets too large, mammals enjoyed an “explosion of diversity” across the world.

“This may have helped drive the recovery. With so many different species evolving in different directions in different parts of the world, evolution was more likely to stumble across new evolutionary paths,” said Longrich.